OBJECTIVETo investigate the effect of decreased expression of high mobility group Box-1 on the proliferation and apoptosis of HepG2 cells.

METHODSThree specific siRNAs of HMGB1 were designed and synthesized, and were transiently transfected into HepG2 cells by Lipofectamine 2000. The HMGB1 expression in HepG2 cells was detected by RT-PCR and Western blotting respectively. The proliferation activity in vitro was assessed by MTT assay. In situ apoptosis was evaluated by terminal deoxynucleotidyl transferase-deoxyuridine triphosphate nick end labeling (TUNEL) assay.

RESULTSAll of these specific HMGB1-siRNAs (1, 2, 3) efficiently and specifically inhibited the expression of the HMGB1 gene, and the levels of HMGB1 mRNA were 1.147+/-0.024, 1.014+/-0.042, 0.435+/-0.055, respectively, in HMGB1-siRNAs transfection group, which were significantly lower than that in Lipofectamine 2000 alone group (1.411+/-0.065, P < 0.01). Correspondingly, all of these specific HMGB1-siRNAs (1, 2, 3) could efficiently and specifically inhibit the expression of the HMGB1 protein, and the levels of HMGB1 protein were 0.369+/-0.035, 0.340+/-0.028, 0.097+/-0.020, respectively, in HMGB1-siRNAs transfection group, which were significantly lower than that in Lipofectamine 2000 alone group (0.553+/-0.051, P < 0.01). Of the 3 specific HMGB1-siRNAs, HMGB1-siRNA-3 (siRNAH3) had the highest inhibition rate (80%). The proliferation of HepG2 cells was markedly inhibited by siRNAH3 transfection. Compared to mock-transfection, siRNAH3 transfection dramatically suppressed the proliferation of HepG2 cells (P < 0.01). Moreover, siRNAH3 can induce apoptosis (P < 0.01).

CONCLUSIONsiRNA targeting HMGB1 mRNA can specifically reduce HMGB1 gene and protein expression. siRNAH3 can effectively suppress the proliferation and induce apoptosis of HepG2 cells.